1. Field of the Invention
The present invention relates to a wire cut electric discharge machine, particularly to a wire cut electric discharge machine with rollers. By using the rolled wire electrode, this invention can reduce the cutting width limit. It can improve the precision of the product, without changing the original material property of the wire electrode. And, it can reduce the cost of the wire electrode.
2. Description of the Prior Art
As shown in FIGS. 8 to 11, the traditional wire cut electric discharge machine comprises a machine 80 and a wire electrode 84.
The machine 80 has a feeding portion 81 and a receiving portion 82. There is a working zone 83 between the feeding portion 81 and the receiving portion 82.
The wire electrode 84 is disposed in the working zone 83. It is constantly fed from the feeding portion 81 and enters into the receiving portion 82. This wire electrode 84 has a circular cross-sectional area that has a predetermined diameter. By using this wire electrode 84, it can cut a workpiece (not shown) by the traditional electric discharge machining method.
However, the disadvantages can be summarized as follows:
[1] It cannot break through the current cutting width limit. The smallest size (which means its diameter) of the current cheaper cupper made wire electrode is roughly 50 μm. But, due to the rapidly growing microstructure industry, the current cutting width limit needs to be broken.
[2] The reduction for diameter is limited by its material property. If the user just simply reduces the diameter of wire electrode, this wire electrode will be easily broken by a pulling force (during the feeding process) or will be melt out due to high temperature (caused by the electric discharge heat). So, the diameter cannot be simply reduced under its material property requirement (such as its tensile strength limit, melting point, etc.). Currently, the minimum diameter of the copper made wire electrode is approximately 50 μm.
[3] The cost of 30- μm wire electrode is high. Concerning the microstructure machining, the tungsten made wire electrode with 30 μm is the most popular one (almost one half of the diameter of the copper made one, 50 μm). But, the major disadvantage is too expensive. Particularly, it is not suitable for mass production. Besides, except the diameter 30 μm, there must be certain gaps (roughly 5 μm each) on both sides. As a result, the minimum cutting width should be roughly 40 μm (30+5+5). That is, if a width of slot is less than 40 μm, it cannot be cut by any existing wire electrode.